Impact of Inoculation Protocols, Salinity, and pH on the Degradation of Polycyclic Aromatic Hydrocarbons (PAHs) and Survival of PAH-Degrading Bacteria Introduced into Soil

Abstract

Degradation of polycyclic aromatic hydrocarbons (PAHs) and survival of bacteria in soil was investigated by applying different inoculation protocols. The soil was inoculated with Sphingomonas paucimobilis BA 2 and strain BP 9, which are able to degrade anthracene and pyrene, respectively. CFU of soil bacteria and of the introduced bacteria were monitored in native and sterilized soil at different pHs. Introduction with mineral medium inhibited PAH degradation by the autochthonous microflora and by the strains tested. After introduction with water (without increase of the pore water salinity), no inhibition of the autochthonous microflora was observed and both strains exhibited PAH degradation.

Is biochar a source or sink for polycyclic aromatic hydrocarbon (PAH) compounds in agricultural soils?

“…Soils inherently contain complex autochthonous microbial communities, which will have contrasting PAH degrading abilities (Ding et al, 2010). Both soil types used in this study contained detectable concentrations of 11 of the 16 USEPA PAHs, with significantly higher levels in the Eutric Cambisol compared to the Cambic Podzol, the lower pH of which may have been important for influencing the breakdown of PAHs (Kastner et al, 1998). In addition, the Podzol had much higher levels of SOM and dissolved organic C content, which have previously been suggested to lead to higher PAH concentrations due to the higher sorptive capacity of the soil (Macleod & Semple, 2002).…”

“…Alternatively, as biochar can stimulate microbial activity in soil (Kolb et al, 2009;Steinbeiss et al, 2009;Quilliam et al, 2012a) its addition could facilitate the degradation of naturally occurring PAHs. Microbial degradation of PAHs in soil is strongly influenced by a number of factors, including pH, soil type, aeration and nutrient and water availability, in addition to the physio-chemical properties of the PAH, its concentration in the soil, the presence of a microbial community capable of degrading PAHs and its relative bioavailability (Cerniglia, 1992;Kastner et al, 1998;Breedveld & Sparrevik, 2000;Volkering & Breure, 2003;Zhang et al, 2006;Ding et al, 2010). As biochar is particularly effective at adsorbing and sequestering organic contaminants, enhanced sorption of hydrophobic organic compounds such as PAHs could actually decrease microbial mineralization by decreasing bioavailability (Rhodes et al, 2008(Rhodes et al, , 2010Xia et al, 2010), and could lead to localized PAH accumulation.…”

Polycyclic aromatic hydrocarbons and volatile organic compounds in biochar and biochar‐amended soil: a review

“…In particular, at low contaminant concentrations (<10-6 solubility), carbonaceous materials, including char, charcoal, and coal, are the primary geo-sorbents (Macloed & Semple, 2002). Microbial degradation of organic compounds in soil is strongly influenced by many factors such as pH, soil type, soil aeration, soil nutrient status, water availability, bioavailability of PAHs, and the presence of a microbial community capable of degrading PAHs (Cerniglia, 1992;Kastner et al, 1998;Breedveld & Sparrevik, 2000;Volkering & Breure, 2003;Zhang et al, 2006;Ding et al, 2010). Furthermore, apart from the pyrolytic gases, biochar has the ability to absorb volatile compounds present in the environment that could influence the sorption behavior of diverse organic contaminants with structurally similar functional groups (Cheng et al, 2008).…”

Advances in the field of high‐molecular‐weight polycyclic aromatic hydrocarbon biodegradation by bacteria

“…It was demonstrated to grow on pyrene microcrystals formed by sonication with and without silicone oil (Mutnuri et al, 2005) and under these conditions biodegradation was enhanced. Pyrene and fluoranthene biodegradation by strain B9 were also assessed in soil under different conditions including variable pH (Kästner et al, 1998).…”